Those gentle eyes of a Labrador retriever that melt the hearts of human companions are also often suspectible to failing the dog through blindness. Unfortunately, there are several causes of vision loss associated with this breed of dog. Being aware of the potential helps owners prepare should blindness strike.
Membrane Separation in Retina
The retina of a Labrador retriever is composed of six layers of thin, delicate membranes that collect visual information from the light passing across the retina. If any of these layers is altered, the visual information becomes skewed and is no longer accurately relayed to the central nervous system where the brain processes sight. Labrador retrievers are prone to having the outer layers of the retina membrane separate from the underlying layers attached directly to the eyeball. This separation, known in veterinary terms as retinal dysplasia, causes the layers to "fold over" on top of each other. This not only causes light from passing through to be interrupted, it also cuts off necessary blood supply to maintain healthy tissue. There is no cure for this type of blindness, which can afflict a dog as young as two months of age and expresses itself rather quickly, causing human companions to describe it as sudden blindness.
Reduction of Retinal Blood Vessels
Unlike the separation of retinal membranes, this ailment -- also known as progressive retinal atrophy -- takes its time in developing full blindness. It begins because the blood vessels bringing the necessary blood supply and nutrients to the retinal tissue stop working. Veterinary researchers are still attempting to explain why the biological tissue backfires as this disorder is common among Labradors as well as other breeds of canine companions. The blindness caused by this progressive loss is usually first noticed at night or in low-light conditions. The dog begins to experience tunnel vision and can only see directly in front of him. Eventually the dog loses visual ability during daylight. This condition is currently incurable and irreversible. Due to the slow progression of this vision-robbing disease, most dogs can function fairly normally if they remain in familiar surroundings.
This opaque covering that builds up on the outside portion of the lens of the dog's eye can occur in any breed of dog. However, for reasons still unknown, Labrador retrievers have a high tendency for developing this condition that causes the dog's eye to appear a milky bluish color. Veterinary researchers attribute the formation of this opaque covering to an abnormal water and calcium content within the lens of the eye. Surgical removal is available. Some veterinarians specialize in the removal of cataracts.
The American College of Veterinary Ophthalmology recommends puppies be screened for eye-oriented disorders by six weeks of age. The college helped a group of Labrador breeders establish a clearinghouse called the Canine Eye Registration Foundation through which breeders can have their sires, bitches and resulting offspring examined for genetically-linked eye disease. Dogs passing receive a 12-month health clearance. Breeders are advised to discontinue the use a dog that does not pass. The college also provides member breeders with research updates gathered by the North American Veterinary Teaching Hospitals. Potential puppy purchasers are advised to ask breeders if their dogs are cleared by ACVO's eye registry.
- chocolate lab image by Lori Boggetti from Fotolia.com
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